The present invention relates to a service node connectable to a telephony network, in which a plurality of peripheral devices are provided, along with switching means for connecting said peripheral devices to external communication means under the control of control processing means.
Over recent years, telephony networks have become more sophisticated and it has become possible for an increasing number of services to be provided, in addition to the fundamental provision of allowing a first customer to be connected to a second customer.
Telephony systems of this type are often referred to as intelligent networks, and provide such services as automatic call distribution, store and forward, fax to speech, call queuing, voice menu systems, call diversion, follow-on and voice prompts, etc.
Service nodes are units within the network where intelligent services are concentrated and made available to customers connected to the network via switching mechanisms provided within the network. At the node itself, a large switching device is provided which allows customer calls to be connected to peripheral devices under the control of central control processing means, such as a mini or mainframe computer. In known systems, an incoming call is connected to a digit collector to collect, or receive, digits (i.e. signalling information) generated by a calling customer, in order that peripheral devices may be connected and, as necessary, disconnected etc. Thus, once a particular service has been established, this is generally driven under the control of a particular peripheral device. However, it is necessary for the central control computer to observe the operation of a connection between peripheral devices and external lines, in order to ensure that the integrity of the overall network is maintained.
A problem with known service nodes is that it is desirable to have large switches at the nodes, so that maximum benefit may be gained from a large number of shared services. However, as the number of shared services increases, with a resulting increase in the size of the connecting switch, the size and power of the control computer must also increase, along with the bandwidth of the communicating link between the computer and the switch.
It will be appreciated that the use of dual tone multi-frequency (DTMF) receivers to receive and decode routing digits or other command signals is well known in the art as is exemplified by the following prior published documents.
U.S. Pat. No. 4,879,743 discloses a PBX system which is responsive to an incoming call directed to an adjunct of the system, for example a voice messaging system, for sending a ringing signal to the adjunct. When the adjunct goes off-hook, the PBX outputs to the adjunct dual tone multi-frequency (DTMF) signals containing information associated with the incoming call prior to establishing a connection between the adjunct and the incoming call. The information includes a mode code for selecting the required operating mode of the adjunct, and also includes the calling and called numbers. Following the sending of this information to the adjunct, the PBX then sends a disconnect mode code to command the adjunct to go on-hook, and subsequently connects the adjunct and the incoming call. During this connection, the adjunct may use in a well-known manner prerecorded voice response to prompt the calling party to enter DTMF digits to access a particular operating capability of the adjunct.
In this U.S. Pat. No. 4,879,743, the adjunct, which is a program-controlled device, has to identify which of the set of mode codes of the form ##nn, where n is a numerical digit in the range 0 to 9, has been received, and, in response to a particular mode code identification, switch to the corresponding operational mode. It does not communicate the received mode code to the PBX or any other adjunct or terminal equipment attached to the PBX.
U.S. Pat. No. 5,181,283 discloses an arrangement for providing pre-authenticated access from a caller to a service provider. The caller dials the number of the service provider, and his local switching system routes the call to an originating service office (OSO). The dialled number is passed by the OSO to a network control point (NCP) which translates the dialled number to a non-dialable directory number (NDDN) together with the identity of an action control point (ACP) having as appropriately equipped associated network services complex (NSC) for routing the call to the destination service provider terminal, and returns this information to the OSO. The OSO forwards this information to the ASP which queries a direct services dialling data base network control point (DSD NCP). The DSD NCP returns a message to the ACP a voice announcement message identification and a reply format indentification including the number of digits expected from the customer. This information is the passed to the NSC which conducts the subsequent exchange with the customer. The NSC detects the DTMF digits keyed by the customer in response to a prompt, these being a personal identification number (PIN) and, if the customer's account number has not been obtained using his originating telephone number and a lookup table, an account number. The NSC sends to the DSD NCP a message including the customer's account number and the NDDN. The DSD NCP checks that the desired service provider has an individual customer account file corresponding to the supplied account number, and provides to the NSC the PIN corresponding to the supplied account number. Upon receipt of the requested information, the NSC verifies that the caller has been authorised to access the service provider, by comparing the PIN provided by the customer with the PIN provided by the DSD NCP, and sending a message to the ACP to forward the call request together with the caller's account number to the service provider. There is no disclosure of digit collection for any purpose other than establishing an authorised call, involving routing digits, account number digits, and PIN digits.
The article "The AT&T Service Circuit Node: A new element for providing Intelligent Network services" by Hall et al, AT&T Technical Journal, vol. 70, no. 3/4, 1991 Short Hills U.S., pages 72-84, discloses a stand-alone service-circuit node that connects to AT&T's 5ESS switching centres. The node comprises a control computer; a number of switch-fabric units; and a collection of service circuits which provide such capabilities as voice announcements, DTMF receivers, and text-to-speech conversion units. When a call is directed to the node from a 5ESS office, in response to recognition by the office that a special service is required because the dialled digits (control information) do not represent a network destination for which the office can proceed to effect a connection, the control information is sent to the control computer, which determines the service to be performed and instructs the switch-fabric unit to connect the call to one or more service circuits (sequentially) to collect digits, play announcements, receive and record a fax transmission, play a message through a text-to-speech unit, etc. The article merely mentions that an incoming call can be connected to a digit collecting service circuit. The conventional use of received digits in these circumstances would be as a response to a voice prompt (announcement), e.g. to collect an account number or PIN, or to make a selection from an offered menu.